fix(help): Ensure padding isn't stripped

Fixes #5083

clap_builder/src/builder/styled_str.rs

@@ -47,6 +47,19 @@ impl StyledStr {
         self.0 = self.0.trim().to_owned()
     }
 
+    pub(crate) fn trim_start_lines(&mut self) {
+        if let Some(pos) = self.0.find('\n') {
+            let (leading, help) = self.0.split_at(pos + 1);
+            if leading.trim().is_empty() {
+                self.0 = help.to_owned()
+            }
+        }
+    }
+
+    pub(crate) fn trim_end(&mut self) {
+        self.0 = self.0.trim_end().to_owned()
+    }
+
     #[cfg(feature = "help")]
     pub(crate) fn replace_newline_var(&mut self) {
         self.0 = self.0.replace("{n}", "\n");

clap_builder/src/output/help.rs

@@ -30,8 +30,10 @@ pub(crate) fn write_help(writer: &mut StyledStr, cmd: &Command, usage: &Usage<'_
         }
     }
 
-    // Remove any extra lines caused by book keeping
-    writer.trim();
+    // Remove any lines from unused sections
+    writer.trim_start_lines();
+    // Remove any whitespace caused by book keeping
+    writer.trim_end();
     // Ensure there is still a trailing newline
     writer.push_str("\n");
 }

tests/builder/help.rs

@@ -1342,7 +1342,7 @@ fn dont_strip_padding_issue_5083() {
             Command::new("two"),
             Command::new("three"),
         ]);
-    static EXPECTED: &str = "one    
+    static EXPECTED: &str = "  one    
   two    
   three  
   help   Print this message or the help of the given subcommand(s)